ChangeSet 1.1123.18.1, 2003/08/11 14:36:10-07:00, trini@kernel.crashing.org

[PATCH] I2C: Fix for i2c-piix4 with on some boards

Hello all.  On some boards with an Intel PIIX4 the BIOS (such as the one
found on a Force CPCI-735) will incorrectly configure the chipset, and
leaves a register in an undefined state causing i2c to behave strangley.
The following patches (first vs lm_sensors-2.8.0 and then vs
2.6.0-test3)  fixes the issue.


 drivers/i2c/busses/i2c-piix4.c |    9 +++++++++
 1 files changed, 9 insertions(+)


diff -Nru a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
--- a/drivers/i2c/busses/i2c-piix4.c	Fri Aug 15 11:27:13 2003
+++ b/drivers/i2c/busses/i2c-piix4.c	Fri Aug 15 11:27:13 2003
@@ -160,6 +160,15 @@
 	}
 
 	pci_read_config_byte(PIIX4_dev, SMBHSTCFG, &temp);
+
+	/* Some BIOS will set up the chipset incorrectly and leave a register
+	   in an undefined state (causing I2C to act very strangely). */
+	if (temp & 0x02) {
+		printk("Fixed I2C problem on Force CPCI735\n");
+		temp = temp & 0xfd;
+		pci_write_config_byte(PIIX4_dev, SMBHSTCFG, temp);
+	}
+ 
 	/* If force_addr is set, we program the new address here. Just to make
 	   sure, we disable the PIIX4 first. */
 	if (force_addr) {